The Evolution of the Sciences 



forth with perfect clearness the terms and the 

 elements of the problem, they were compelled 

 to stop half way; the problem now required 

 the application of methods which thermo- 

 dynamics had already employed and tested 

 in the study of purely physical states of equili- 

 brium. Hence, while French science was 

 delayed by other researches, physico-chemical 

 laboratories were being opened at Amsterdam, 

 Leyden, Gottingen, Leipzig, Berlin and Ithaca, 

 with the object of developing theoretically 

 and practically chemical mechanics. To-day, 

 thanks to these efforts, the laws of chemical 

 equilibrium are known at least in part. Chemi- 

 cal dynamics is, however, barely sketched out, 

 and is limited at present to a simple classi- 

 fication of the reactions observed when the 

 temperature and pressure of a system are 

 varied; one exception deserves to be made 

 in favour of explosive reactions. The neces- 

 sary study of explosives has contributed 

 to chemistry by accumulating much work 

 on this subject; the important part taken 

 by MM. Vieille and Berthelot in these studies 

 is well known. 



54 



